Disclosed embodiments relate to total air temperature (TAT) probes or sensors. More particularly, the present embodiments relates to improving deicing heater error (DHE) performance in TAT probes.
Modern jet powered aircraft require very accurate measurement of outside air temperature (OAT) for inputs to the air data computer, engine thrust management computer, and other airborne systems. For these aircraft types, their associated flight conditions, and the use of total air temperature probes in general, air temperature is better defined by the following four temperatures: (1) Static air temperature (SAT) or (TS), (2) total air temperature (TAT) or (Tt), (3) recovery temperature (Tr), and (4) measured temperature (Tm). Static air temperature (SAT) or (TS) is the temperature of the undisturbed air through which the aircraft is about to fly. Total air temperature (TAT) or (Tr) is the maximum air temperature that can be attained by 100% conversion of the kinetic energy of the flight. The measurement of TAT is derived from the recovery temperature (Tr), which is the adiabatic value of local air temperature on each portion of the aircraft surface due to incomplete recovery of the kinetic energy. Temperature (Tr) is in turn obtained from the measured temperature (Tm), which is the actual temperature as measured, and which differs from recovery temperature because of heat transfer effects due to imposed environments. For measuring the TAT, TAT probes are well known in the art. These probes can be of a wide range of different types and designs, and can be mounted on various aircraft surfaces which expose the TAT probe to airflow. For example, common TAT probe mounting locations include aircraft engines and aircraft fuselages.
Conventional TAT probes, although often remarkably efficient as a TAT sensor, sometimes face the difficulty of working in icing conditions. Anti-icing performance is facilitated by heater elements embedded in or around the housing walls of TAT probes or from hot air flowing through the probes (e.g., from an aircraft engine). Unfortunately, external heating also heats the internal boundary layers of air which, if not properly controlled, provide an extraneous heat source in the measurement of TAT. The heat used to de-ice TAT probes causes an error in the temperature reading known as de-icing heater error (DHE). Deicing Heater Error is difficult to correct for.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.